Biometrics is the science and technology of measuring and analyzing biological data, such as the imagery of the face or iris. There are 3 problems that need to be overcome with the acquisition of biometric data: (i) ensuring that the biological data is within the field of coverage of one or more of the biometric sensors which is often difficult to control precisely since the sensors may be mounted in different ways for different deployments, and (ii) ensuring that the data is acquired as uniformly as possible so that comparison of data from the same user across different time periods is facilitated, and (iii) ensuring that the user is looking in the vicinity of the camera systems used in any face or iris recognition system